Lock decoder



Sept. 23, 1941. H. HOFFMAN' .2,257,054l

LOCK DECODER Filed June 12, 1940 2 sheets-sheet 1 *mi* 5 Hara/d H7 /fmn 33h Mw Cul Sept' 23, 1941- H. HOFFMAN LOCK DECODER Filed June 12, .1940 2 Sheets-Sheet 2 Amm Patented Sept. 23, 1941 UNI-TED STATES oFFicE 6 Claims.

This invention relates to lock decoders and has, as a general object, the provision of a convenient simple mechanism for quickly and accurately decoding pin tumbler locks.

Another object of this, invention is to provide a decoder wherein a key blank is utilized to successively manipulate the respective tumblers in the lock and wherein the key blanks are detachably clamped in place to enable the decoder to be used with a wide variety of locks.

A further object of this invention is to provide a decoder of sufficiently rugged construction to withstand hard usage and so constructed that the initial motion obtained from the measurement of the pin tumbler lengths is multiplied considerably to insure accurate measurement.

With the above and other objects in view which will appear asthe description proceeds, this invention resides in the novel construction, combination and arrangement of parts substantially as hereinafter described, and more particularly defined by the appended claims, it being understood that such changes in the precise embodiment of the hereindisclosed invention may be made as come within the scope of the claims.

The accompanying drawings illustrate one complete example of the physical embodiment of the invention. constructed in accordance with the best mode so far devised for the practical application of the principles thereof, and in which:

Figure i is a perspective View of a decoder constructed in accordance with this invention and illustrating its manner of use;

Figure 2 is a top plan View of the decoder with the scale and pointer removed;

Figure 2a is a detail sectional View through Figure 2 on the plane of the line 2cv-2a;

Figure 3 is an enlarged sectional View through a lock with the blade of the decoder in place to show the manner in which the vmeasurement of the tumbler lengths is effected;

Figure 4 is a detail sectional View taken through Figure 3 on the plane of the line 4 4;

Figure 5 is a detail cross sectional view taken through Figure 3 on the plane of the line 5-5; and

Figure 6 is a perspective view of one of the blank key blades used with the decoder.

Referring now particularly to the accompany- .ing drawings, in which like numerals indicate like parts, the numeral 5 designates the supporting body or base of the key decoder. It is preferably a die casting shaped to provide a convenient grip to enable the same to be grasped in one hand as shown in Figure 1.

At its front end, the body or base has a recess E for the reception of a key blank l. The key blank is removably clamped in the `recess between two plates 8 loosely retained in the recess by a cross pin 9. i

Set screws iii threaded into the opposite walls of the recess bear against the plates to clamp them against the head of the key blank which, as best shown in Figure 6, is cut to provide a shoulder or abutment l l. This shoulder or abutment must be brought firmly against the front face of the base to properly locate the blank with respect to the base. Y

The offset or stepped formation of the key blank also serves to position the top edge l2 of the blank directly under and adjacent to a rod-l like feeler i3 of a depth gauge slidably mounted in the body or base. The rod-like feeler I3 projects forwardly from and is fixed with relation to a rack |13. The rack is preferably of cylindrical cross section so as to slidably fit in a 1ongitudinai bore l5 in the body. Itsraek teeth :a

mesh with a pinion Il fixed to a pointer stem.

This pointer stem has its inner end journalled in the bottom of a counterbored well I9 opening to the top face of the body and has its medial portion journalled in a bearing bushing 2D seated in the oounterbore of the well. Inasmuch as the bushing bears down on top of the pinion, its

- securement in the counterbore holds the pointe A pointer 23 nonrotatablyriixed to the uppery projecting end of the stem I8 is arranged to traverse the dial which is graduated in a manner to be hereinafter described.

Alongside the bore E5 is a longitudinal cavity or groove 24 opening to the top face of the body and communicating with the bore l5 at its rear end through a slot 25. 'Ihe cavity or groove 24 has a tension spring 2t mounted therein. One end of the spring is anchored to the base, as at 21, and its other end is hooked onto a pin 23 secured in the rear end portion of the rack and passing through the slot 25 into the cavity or groove 2t.

The connected pointer and rack with its rodlike feeler projecting from the front end thereof are thus yieldingly urged to a normal inactive position dened by the engagement of the abrupt shoulder 29 formed at the juncture of the rack and feeler with the bottom of the bore I5.

As will be readily apparent, inward depression of the feeler I3 against the tension of the spring 26 turns the pointer stem and swings the pointer in a counterclockwise direction, as viewed in Figure 1.

The dial is divided into first, second, third, fourth and fifth pin areas, as indicated in Figure r1. Each area is a segment of the entire circle and each of these separate areas is divided into four spaces representing the second, third, fourth and fifth key notch depths of a key for use in a five tumbler lock.

VThe first notch depth actually is the top edge of the key and therefore requires no cutting. This position is indicated on the dial during the Vdecoding of a lock by the stop areas which divide the pin areas from each other, as clearly shown in Figure 1.

Between the first and fifth pin areas, is a segmental area designated Start within which the pointer must lie at the beginning of the decoding operation. y

In decoding a lock, a blade of the proper type to'flt thelock is clamped in place and then with the decoder gripped, as shown in Figure 1, the blade is inserted Vinto the key slot of the lock. As the blade is inserted into the key slot, the end of the rod-like feeler I3 bears against the frontface of the lock, as clearly shown in Figure 3 so that upon continued insertion of the blade, relative motion takes place between the blade and the feeler which motion is translated into rotation of the pointer through the rack and pinion.

When the pointer moves to a position overV the S of the word Start, the nose or point of the key blade will just contact the-.first tumbler. With the decoder held at Vthis position, it is twisted to impart a turning force on the cylinder 30 of the lock.

While the cylinder cannot actually be turned, the play in the parts is sufficient to enable disalignment between the tumbler bores 3l in the cylinder andthe driver bores 32 in the casing 33 of the lock.

Hence, if the key blade is moved inwardly while the twisting strain is maintained on the cylinder, the first tumbler will be lifted to push its driver out of the cylinder'and to engage its upper end with'the shoulder formed by the edge of the Vbore 32, as Vshown in Figure 4.

When this Yposition is reached, the pointer will have moved across the first pin area to a position at which it will indicate the key notch depthY corresponding to the length of the first tumbler. If this first vtumbler requires a key notch depth of the second, third, fourth or fth position, the pointer will sto-p at one of these indications; but if it Ycalls for a No. 1 depth, the pointer will move into the, stop area whichrdivides the first and second pin areas.

After the first tumbler is measured in this mannenvthe twisting strain is released and the `blade is pushed in until the pointer occupies the stop position between the first and second pin areas and thereafter, the process is repeated `to measurethe second tumbler.

Obviously, these steps are repeated foreach tumbler of the'lock in the matter stated. The entire combination is thus quickly and accuratelyV determined.

From the foregoing description taken in connection with the accompanying drawings, it

will bereadily apparentthat this invention pro-l vides a simple relatively rugged key decoder' for quickly and accurately decoding the combination of vany pin type tumbler lock.

What I claim as my invention is:

1. A lock decoder for determining the combination of a pin tumbler lock having a lock cylinder rotatable in a casing and having pin tumblers o f dierent lengths and spring pushed drivers, the junctures between which must be aligned with the line of part between the cylinder and casing to enable rotation of the cylinder, said decoder comprising: a base; a blade fixed to the base and projecting therefrom for insertion into the lock; a movable feeler projecting from the base adjacent to the blade for engagement with an outer face of the lock; means yieldingly urging the feeler outwardly so that upon insertion of the blade into the lock to successively engage the pin tuinblers, said feeler is moved progressively into the base distances determined by the length of the successive tumblers; a scale member and a cooperating indicator member carried by the base, said scale member being calibrated to represent different key notch depths, one of said members being movable with relation to the other; and means for translating motion of the feeler into a coordinated motion of the movable one of said members.

2. A lock decoder for determining the combination of a pin tumbler lock having a lock cylinder rotatable in a casing and having pin tumblers of different lengths and spring pushed drivers, the junctures between which must be aligned with the line of part between the cylinder and casing to enable rotation of the cylinder, said decoder comprising: a base; a blade Xed to the base to project forwardly therefrom for insertion into the key slot. of a lock; a movable feeler projecting from-the base adjacent to the blade to engage the front face of a lock; a spring urging the movable feeler outwardly to a prebination of a pin tumbler lock having a'lockA cylinder rotatable in a casing and having pin tumblers of different lengths and spring pushed drivers, the junctures between which must be aligned with the line of part between the cylinder and casing to enable rotation of the cylinder, said decoder comprising: a base; a blade of substantially key blank configuration; means for clamping the blade to the base so that the blade projects forwardly therefrom for insertion into the key slot of alock; almovable feeler projecting from the base adjacentto the blade to engage the front face of a lock; a spring urging the movable feeler outwardly to a predetermined extreme position so that upon insertion of the blade into the lock, said feeler is moved into the base a distance determined by manipulation of the blade in the lock to progressively lift the tumblers to their unlocked positions so that the inward motion of the feeler corresponds to the length of the successive tumblers; a scale calibrated in key notch depths fixed to the base; a pointer movable across the scale; and a driving connection between said feeler and the pointer whereby motion of the feeler swings the pointer across the scale to indicate key notch depths corresponding to the lengths of the successive tumblers.

4. A lock decoder of the character described comprising: a supporting body formed to provide a convenient hand grip; a blade of substantially key blank configuration; means at the front of the supporting body for securing the blade thereto in a position projecting forwardly therefrom; a plunger mounted for endwise motion relative to the blade supporting body and having an end portion projecting forwardly therefrom to occupy a position adjacent to the blade in place; a spring urging the plunger outwardly of the supporting body to a predetermined extreme position; a dial member calibrated to represent dierent key notch depths; an indicator member; means mounting both of said members on the supporting body, one of said members being movable with relation to the other; and a driving connection between the plunger and the movable one of said two members.

5. A lock decoder of the character described comprising: a supporting body formed to provide a convenient hand grip; a blade of substantially key blank configuration; means at the front of the supporting body for holding the blade in a position thereon projecting forwardly of the supporting body; a plunger slidably mounted in the supporting body and having an end portion projecting forwardly therefrom to occupy a position adjacent to the blade in place; a spring urging the plunger outwardly of the supporting body to a predetermined extreme position; a dial secured to the supporting body and calibrated to represent different key notch depths; a movable pointer; means mounting the pointer from the supporting body to traverse the dial; and a driving connection between the plunger and said movable pointer.

6. A lock decoder for pin tumbler locks comprising: a grip; a blade adapted to be fixed to the grip and having an end portion insertible into the key slot of a pin tumbler lock to engage the tumblers thereof; a feeler mounted adjacent to a blade in place on the grip for substantially endwise motion in a direction lengthwise of the blade, said feeler having an end portion normally adjacent to said end portion of the blade and engageable with a portion of the lock when the blade is inserted into the key slot of the lock; means yieldingly urging the feeler in a direction toward said end of the blade; a dial calibrated to represent different key notch depths; an indicator cooperating with the dial; and means for translating motion of the feeler relative to the blade produced by inserting the blade into the key slot of the lock into relative motion between the dial and indicator.

HAROLD HOFFMAN. 

